One dam thing after another

Though the Mekong is in peril, riparian governments seem oddly insouciant

CLIMATE change threatens the Mekong river, continental South-East Asia's lifeblood, at both source and mouth. As glaciers shrink in the Tibetan Himalayas from where the river springs, so will the snow melt that helps to feed it; as sea levels rise, salination will worsen in the Mekong delta in Vietnam at the far end of its 5,000km (3,200-mile) length. Yet it is what is planned in between—no fewer than 19 dams on the mainstream, in addition to dozens on its tributaries—that is terrifying ecologists. The flows of fertile sediment that have for centuries sustained farmers along the Mekong's banks will diminish. Species of fish that have provided livelihoods and protein for millions of people (some 60m live in the lower Mekong basin) are unlikely to survive the obstacles to their migrations.

Four dams have already been built and another is under construction on the northern half of the river in China, which is hungry for its hydroelectric potential. China argues that its full “cascade” of eight dams, to be completed within a couple of decades, will enable it to help avert the dreadful wet-season flooding to which the region is prone—this year, of course, above all. Yet downstream countries—Laos, Thailand, Cambodia and Vietnam—are nervous about the control over them this will give China. Of more immediate concern is the Laotian government's determination to build the first mainstream dam south of China, at a place called Xayaburi. It is already building roads to the site, despite calls for a delay from Vietnam, supported by the Mekong River Commission, an intergovernmental body grouping together the four lower-basin countries.

The commission is to meet from December 7th-9th, partly to discuss the Xayaburi project. But as a spokesman for its secretariat puts it: “no country has a veto”. It is merely a consultative and research body, not a transnational regulator. The $3.5 billion project, promoted by a Thai developer and involving a dam 850 metres (2,800 feet) wide with a 60km-long reservoir behind it, would generate 1,260MW of power. It seems to have almost unstoppable momentum. Laos's government has long seen exports of electricity to Thailand as offering its best chance of bringing prosperity to its 6.5m people, most of whom live in poverty. A 2010 study (“The Mekong; River under Threat”) by Milton Osborne of the Lowy Institute, an Australian think-tank, cites an estimate of 77 “live” dam projects in the country.

Of the world's rivers, only the Amazon has more species of fish than the Mekong. Most are migratory, and experts believe the planned dams will endanger many of them. Michio Fukushima, of the National Institute for Environmental Studies in Japan, who has spent five years studying the Mekong's fish, says no one really knows the impact Xayaburi alone would have. Fishery is one of the many aspects of the environmental-impact assessment prepared for Xayaburi's developers that has been flayed by experts as woefully inadequate. The real fear, however, is that once that project goes ahead, the taboo on the downstream construction of dams would be broken. Others would follow.

The country most at risk from this is Cambodia. By some estimates seven-tenths of Cambodians' consumption of animal protein comes from fish caught in the Mekong or in its great lake, the Tonle Sap. At its low point, the Tonle Sap has an area of 2,700 square kilometres (1,000 square miles), much of it just a metre deep. In the wet season it more than doubles in area with a depth in some places of nine metres. As it starts to empty, each October or November, 50,000 fish a minute swim out of the lake.

So it is puzzling that Cambodia, though it has expressed reservations about Xayaburi, is not up in arms about it. This is a country, after all, that this year risked all-out war with Thailand in a petty spat over a bit of disputed borderland. There are a number of possible explanations. One is that two of the 11 planned downstream dams are in Cambodia itself. Another is that China supports dams and is a generous benefactor to the elected but dictatorial government of Hun Sen, the prime minister. A third is that Cambodia, like Laos, is riven with corruption. A tiny percentage of a billion-dollar project can buy a lot of acquiescence in poor countries.

Perhaps leaders are ignorant of or simply do not believe the weight of scientific evidence against the dams: for instance, experts concur that the mitigation techniques advertised as saving migratory fish, such as ladders, lifts and bypasses, are ineffective. Mr Osborne speculates that another factor is the perception that dams, electricity and mega-projects are the symbols of a modernistic future; fishing and subsistence farming, by contrast, are reminders of a backward past. Bear in mind, too, that both Laos and Cambodia are top-down, one-party states where NGOs are weak and public opinion is not a prime concern. Michael Coe, an expert on South-East Asia at Yale University, makes the comparison to the Soviet Union's devastation of the Aral Sea.

Vietnam, along with the region's environmentalists, is much clearer in its opposition to going ahead with Xayaburi. Laos's willingness to ignore such critics suggests that, these days, the foreign voices it listens to most attentively come from the north, from China.

The otolith race

That Laos's downstream neighbours—both of them partners in the Association of South-East Asian Nations, ASEAN—have no mechanism for stopping its plans shows the limits to regional co-operation. The Mekong River Commission, like ASEAN itself, is about consultation, process and consensus. No member is prepared to cede its national sovereignty, even on an issue as patently transnational as the Mekong. And so Mr Fukushima, whose expertise is in examining otoliths—the ear bones that provide a history of a fish's migratory patterns—says he feels he must hurry to finish his research.